Background. Advances in sound processing technology have led to a proliferation of hearing aids that vary greatly in quality, features, and cost. Although a number of hearing-specific quality of life scales have been developed to measure treatment effect, these scales have been designed to assess overall benefit, rather than to distinguish differences between hearing aids. Specific Aims. To develop and validate a clinically practical questionnaire for hearing aid users that measures the Effectiveness of Auditory Rehabilitation (EAR). This scale will be designed to: 1) distinguish between the effectiveness of different types of hearing aids, and 2) provide insight into how particular hearing aid features affect patient-perceived benefit. This tool is a critical antecedent in the applicant's long-term goal of building a clinical research program to study hearing loss and auditory rehabilitation, including identification of prognostic factors for successful rehabilitation, evaluation of screening programs, and trials of hearing aid innovations. Methods. Data from a pilot trial suggest that patients find important a number of non-hearing issues (e.g., convenience, reliability, and appearance) that are absent from existing quality of life scales. These variables are critical to satisfaction and hearing aid compliance. A taxonomy of these issues, as well as hearing-related concerns, has been created. To develop the EAR scale, questions corresponding to each category of the taxonomy will be assembled, tested in a convenience sample of patients, and modified in an iterative fashion. To psychometrically validate the questionnaire, reliability (test-retest, internal consistency) and construct validity (concurrent, known-groups, and discriminant) will be established in a cohort of patients from three audiology clinics affiliated with the University of Washington. Finally, to establish the responsiveness of the scale, subjects from the validation cohort will return 3 months after receiving their aid for repeat evaluation. We hypothesize that EAR scores will improve the most in patients reporting high rates of satisfaction and compliance.